1. Field of the Invention
The present invention relates to information searching apparatus and method, and a transmission medium, and more particularly to information searching apparatus and method and a transmission medium with which an edition point can be detected by an apparatus having a simple structure and a low price.
2. Description of the Related Art
ATRAC (Adaptive transform Acoustic Coding) (Trademark) used for MD (mini disc) (Trademark) is known as a technique for performing high-efficiency coding by using redundancy of digital audio signals. According to ATRAC, a digital audio signal is blocked every predetermined time length to code spectrum data by utilizing redundancy thereof. Thereafter, the spectrum data are recorded in a magneto-optical disc (MD) together with parameters representing coding conditions.
In order to record a long-time digital video signal into a compact-size recording medium having a small recording capacity, it is indispensable to code the video signal with high efficiency. In order to satisfy such a requirement, various high-efficiency coding systems using correlation of video signals have been proposed, and the MPEG (Moving Picture Experts Group) system is known as one of these high-efficiency coding systems. The MPEG system is a hybrid system in which a motion compensation prediction coding system and a discrete cosine transform (DCT) coding system are used in combination with each other. According to the MPEG system, a frame is divided into blocks (called as xe2x80x9cmacro-blocksxe2x80x9d) for processing. In the processing, redundancy on time axis is cut out by taking a difference between frames, and then redundancy on spatial axis is cut out by using discrete cosine transform, thereby coding video signals efficiently.
In general, the coded signals which are formed by these high-efficiency coding systems are not quantitative, but the information amount thereof varies with time lapse. Therefore, it is known that higher image quality can be obtained by using a variable bit rate coding than by using a fixed bit rate coding for the same coding amount.
When a specific position (for example, represented by a scene change position (this position is hereinafter referred to as xe2x80x9cedition pointxe2x80x9d)) is searched from reproduced signals based on the coded signals coded by the above high-efficiency coding methods, the coded signals are decoded at a higher speed than at a normal speed for reproduction and display. A user searches an edition point from images which are continuously reproduced and displayed at a high speed while viewing these images.
Therefore, for search of an edition point, the performance of a normal decoding and reproducing apparatus is insufficient, and the performance of a higher-speed decoding and reproducing apparatus is required. For example, when an edition point is searched while feeding a recording medium at a speed which is five times as high as the normal decoding and reproducing apparatus, a decoding processor is required to perform decoding processing at a speed which is five times as high as the normal processing speed. Further, in order to support variation of a sampling rate, etc., higher-speed processing is required. A processor which can perform such high-speed processing can be implemented by a parallel processor architecture or the like, however, it is very high in price and more complicated in construction. In an editing apparatus for business, such a high-price process can be used, however, it is difficult to use such a high-price processor in a domestic reproducing apparatus.
Further, there is a case where highly efficiently coded signals are processed in a personal computer (hereinafter merely referred to as xe2x80x9cPCxe2x80x9d). A general purpose processor is used in such a PC, and a decoding method is supplied in the form of a program, so that it is more difficult to perform decoding processing at a higher speed by using a general-purpose processor than by using a special-purpose processor.
The present invention has been implemented in view of such a situation, and has an object to provide information searching apparatus and method, and a transmission medium in which an edition point can be searched with a low-price apparatus having a simple construction.
In order to attain the above object, an information searching apparatus according to the present invention is characterized by comprising extraction means for extracting a parameter associated with coding from data which are obtained by coding predetermined information every predetermined unit, comparison means for comparing a parameter of a predetermined unit with a parameter of another unit, and detection means for detecting an edition point of information in accordance with a comparison result of the comparing means.
An information searching method according to the present invention is characterized by comprising an extraction step for extracting a parameter associated with coding from data which are obtained by coding predetermined information every predetermined unit, a comparison step for comparing a parameter of a predetermined unit with a parameter of another unit, and a detection step for detecting an edition point of information in accordance with a comparison result of the comparing step.
A transmission medium according to the present invention is characterized by transmitting a program comprising an extraction step for extracting a parameter associated with coding from data which are obtained by coding predetermined information every predetermined unit, a comparison step for comparing a parameter of a predetermined unit with a parameter of another unit, and a detection step for detecting an edition point of information in accordance with a comparison result of the comparing step.